Hello Ralph,
Congratulations on the new RV.
I'll try to answer a few of your questions based on how I manage our 2014 Southwind:
1) When storing the RV without shore power, I always shut off the inside battery disconnect switches (2) and the outside inverter switch (1). If you were storing "with" shore power, leave the outside inverter switch on allowing the battery charger to charge all batteries.
2) As for oil changes, my RV mechanic suggested I go with synthetic oil and it literally increased the mileage between changes from 3,000 miles to 6,000 mile, at approx. $110.00/ per change.
3) When storing, I always shut off the propane, just peace of mind.
4) On my Southwind, I have a bi-pass valve for the water heater in the basement compartment beside the wet bay. After the system has been winterized I switch the valve back to "flow" so that in the Spring I can flush it out using city water. I also have a valve coming into the water pump for winterizing with pink anti-freeze. Again, after winterizing, I open the valve so that it is ready for the Spring flush.
Jim